Intragastric stent for duodenum bypass

ABSTRACT

A porous weave of bioabsorbable filaments is encased in an elastic membrane to form a thin-walled stent. The stent is sized to be snugly fitted in the proximate portion of the duodenum of a patient, to induce weight loss by limiting uptake of food passing through the stent. After a predetermined period, the stent degrades and passes from the body without surgical intervention.

FIELD OF THE INVENTION

[0001] The present invention relates to an impervious, resilient,flexible, biocompatible stent that can be secured in the duodenumadjacent to the pylorus to effect weight loss over a controlled period.

BACKGROUND OF THE INVENTION

[0002] The incidence of obesity and its associated health-relatedproblems have reached epidemic proportions in the United States. See,for example, P. C. Mun et al., “Current Status of Medical and SurgicalTherapy for Obesity” Gastroenterology 120:669-681 (2001). Recentinvestigations suggest that the causes of obesity involve a complexinterplay of genetic, environmental, psycho-behavioral, endocrine,metabolic, cultural, and socioeconomic factors. Severe obesity isfrequently associated with significant comorbid medical conditions,including coronary artery disease, hypertension, type II diabetesmellitus, gallstones, nonalcoholic steatohepatitis, pulmonaryhypertension, and sleep apnea.

[0003] Estimates of the incidence of morbid obesity are approximately 2%of the U.S. population and 0.5% worldwide. Current treatments range fromdiet, exercise, behavioral modification, and pharmacotherapy to varioustypes of surgery, with varying risks and efficacy. In general,nonsurgical modalities, although less invasive, achieve only relativelyshort-term and limited weight loss in most patients. Surgical treatmentsinclude gastroplasty to restrict the capacity of the stomach to holdlarge amounts of food, such as by stapling or “gastric banding.” Othersurgical procedures include gastric bypass and gastric “balloons” which,when deflated, may be inserted into the stomach and then are distendedby filling with saline solution.

[0004] The need exists for cost effective, less invasive interventionsfor the treatment of morbid obesity.

SUMMARY OF THE INVENTION

[0005] The present invention provides a novel system for treatment ofmorbid obesity by use of a bioabsorbable stent fitted snugly in theduodenum adjacent to the pylorus and impervious to digestive juices tolimit the uptake of food passing through the stent. The stent isthin-walled, elastic, and flexible so as not to interfere with normalshifting of the duodenum nor with the passage of food therethrough. Thestent can be formed of bioabsorbable material such that after apredetermined period the stent degrades and passes out of the bodywithout the necessity for additional surgical intervention.

[0006] In the preferred embodiment, the stent includes a weave ofbioabsorbable filaments and a covering or coating of impervious materialor membrane. Alternatively, the weave can be integrated within themembrane. The filaments preferably have memory characteristics tendingto exert moderate pressure against the interior wall of the duodenum,and the stent can possess regional variable strength, structure andbioabsorption pharmacokinetics. The stent can be secured in place bysutures at its proximate and distal ends.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The foregoing aspects and many of the attendant advantages ofthis invention will become more readily appreciated as the same becomebetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

[0008]FIG. 1 is a somewhat diagrammatic elevation of a stomach andadjacent parts of the alimentary canal, with the wall of the distalpyloric part and duodenum broken away to reveal an intragastric stent inaccordance with the present invention; and

[0009]FIG. 2 is a side elevation of the stent of FIG. 1 prior toinsertion in the duodenum.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0010] The present invention provides an elastic, flexible, imperviousstent adapted to be secured within a patient's duodenum to limit uptakeof food in that area and thereby assist in weight loss.

[0011]FIG. 1 illustrates a central portion of the alimentary canal,including the distal segment of the esophagus 10, the stomach 12, andthe duodenum 14 (proximate segment of the small intestine). The pyloricpart 16 of the stomach leads to the duodenum 14 by way of the gastricoutlet or pylorus 18. The pylorus forms the distal aperture of thestomach and has an enclosing circular layer of muscle which is normallycontracted to close the aperture but which relaxes to provide an openbut restricted passage. Although subject to substantial variation indifferent individuals, in a representative patient the pylorus has amaximum open diameter of about 2 cm, and the duodenum has a diameterwhich typically is about 18-20 mm in diameter.

[0012] In accordance with the present invention, a flexible, thin-walledstent 20 fits snugly in the duodenum from a location adjacent to thepylorus 18 to a location substantially distally therefrom, approximately6 cm to approximately 12 cm in a preferred embodiment. The stent can beinserted through the esophagus and have its proximate and distal endssecured by endoscopic suturing, which is a minimally invasive procedureas compared to other surgical interventions used for treating morbidobesity.

[0013] With reference to FIG. 2, preferably the stent 20 is formed as athin-walled cylinder including woven filaments 22. The filaments form awoven shell having the desired memory characteristics that maintain thegenerally cylindrical shape and the resiliency that allows the stent tobe compressed and bulged at different locations along its length. Inaddition, the filaments are formed of bioabsorbable material, such aspolyglycolic acid polymer or polylactic acid polymer. The primaryfunction of the fibrous weave is to obtain the desired shape-retainingcharacteristics, but such a weave will typically be porous, or at leastporous enough that digestive juices would pass therethrough andpartially or totally defeat the purpose of the stent in preventinguptake of food through the duodenum. Consequently, the woven filamentsare encased in an impervious elastic membrane 24 or incorporated withinsuch a membrane. The membrane also provides a smooth exterior for thestent, lessening the chance of irritation of the lining of the duodenum.

[0014] Various manners of manufacture of the stent are possible. Thewoven filament part may be formed first and inserted through acylindrical elastic membrane. Another possibility is to insert thefibrous cylinder onto a mandrel and spray or dip the mandrel in asettable liquid which solidifies to form the coating. The woven part ofthe stent also can be spun of fine filaments on a mandrel whichthereafter is sprayed with such a settable liquid, with or without achopped fiber reinforcing material.

[0015] It is preferred for the present invention that the entire stent,including woven filaments and membrane, be bioabsorbable over a periodof time estimated to result in a desired weight loss. Such period couldbe from three months to two years, preferably about six months. At theend of the selected period, the stent degrades and passes from the bodywithout intervention. Due to the noninvasive nature of placement andpassing of the stent, the procedure can be repeated if necessary inorder to achieve the desired weight loss.

[0016] While the preferred embodiment of the invention has beenillustrated and described, it will be appreciated that various changescan be made therein without departing from the spirit and scope of theinvention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. An intragastric stent comprising a substantially cylindrical thin-walled shell sized for snug fitting in a duodenum, the shell having a weave of flexible, resilient filaments and including an elastic peripheral membrane impervious to digestive juices such that, when deployed in the duodenum, uptake of food through the stent is lessened or inhibited.
 2. The stent defined in claim 1, in which the filaments and membrane are bioabsorbable so that the shell will pass from the duodenum without surgical intervention after an approximately predetermined period.
 3. The stent defined in claim 2, in which the approximately predetermined period is 3 months to 2 years.
 4. The stent defined in claim 3, in which the approximately predetermined period is about 6 months.
 5. The stent defined in claim 1, in which the shell has a length of about 6 cm to about 12 cm.
 6. A method of inducing weight loss in a patient which comprises securing in the proximate portion of the duodenum of the patient a substantially cylindrical, thin-walled, flexible elastic stent impervious to digestive juices in the duodenum to limit uptake of food through the stent and along the portion of the duodenum in which the stent is fitted.
 7. The method defined in claim 6, in which the stent includes a weave of. flexible, resilient filaments and an elastic peripheral membrane.
 8. The method defined in claim 7, in which the stent is bioabsorbable so that it will pass from the duodenum within an approximately predetermined period.
 9. The method defined in claim 8, in which the approximately predetermined period is three months to two years.
 10. The method described in claim 9, in which the approximately predetermined period is six months. 